JPS60127308A - Manufacture of chloroprene polymer - Google Patents

Abstract

PURPOSE:To obtain titled polymer curable without any organic curing promotor, capable of giving cured products of high strength and heat deterioration resistance, by performing aqueous emulsion polymerization of chloroprene in the presence of specific amount of cyclic polysulfide compound followed by deflocculation of the polymer formed. CONSTITUTION:A chloroprene polymer latex is first produced by performing aqueous emulsion polymerization of chloroprene in the presence of >=0.1wt% based on said chloroprene, of a cyclic polysulfide compound (e.g. 1,2,3,4-tetrathiacychlohexane) using emulsifier and catalyst. Following that, a deflocculating liquor is added to she resultant latex to carry out a deflocculation followed by removing unreacted chloroprene by e.g. steam stripping then drying by e.g. lyophilization, thus obtaining the objective polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a tetraloprene polymer having high strength and excellent heat resistance.

Chloroprene polymers are broadly classified into sulfur-modified types and non-sulfur-modified types, depending on the chain transfer agent used.

In general, sulfur-modified types that use elemental sulfur as a chain transfer agent can be vulcanized with just metal oxides without using organic vulcanization accelerators such as thiuram, and the vulcanized product has good mechanical properties. Although it has adhesion to other materials, it is known that its heat aging resistance is inferior to non-sulfur-modified types.

On the other hand, non-sulfur-modified types that use mercaptan compounds or xanthogen compounds as chain transfer agents have good heat resistance, but are known to be inferior to sulfur-modified types in mechanical properties such as tensile strength.

Furthermore, in the case of a non-sulfur modified type, it is necessary to use an organic vulcanization accelerator such as ethylene thiourea in order to obtain sufficient vulcanization properties. However, ethylene thiourea, which is currently most commonly used, is suspected of being carcinogenic and there is concern that its use will be banned. For this reason, the development of a vulcanization accelerator to replace ethylene thiourea has been considered, but no vulcanization accelerator superior to ethylene thiourea has yet been found.

In light of the above, there is currently a desire to develop a chloroprene polymer that allows a vulcanizate to be obtained that has both good mechanical properties and heat resistance without using an organic vulcanization accelerator.

In addition, cyclic polysulfide compounds are attracting attention as one of the biologically active compounds, and it is also known that they can be used as crosslinking agents in place of sulfur alone and as monomers for polysulfide polymers.

The object of the present invention is to obtain a chloroprene polymer that can yield a vulcanizate having both good mechanical properties and heat aging resistance without using an organic vulcanization accelerator, namely: This is a method for producing a chloroprene polymer, which is characterized by subjecting chloroprene to aqueous emulsion polymerization in the presence of a cyclic polysulfide compound having a weight of α1 or more, and then peptizing the obtained polymer.

Such a tetraloprene polymer produced according to the present invention can be vulcanized only with a metal oxide without using an organic vulcanization accelerator, and the obtained vulcanizate has excellent heat aging resistance. and has high strength.

The present invention will be explained in more detail below.

The term chloroprene used in the aqueous emulsion polymerization of the present invention means chloroprene alone or a mixture of chloroprene and a monomer copolymerizable therewith.

Examples of copolymerizable monomers include 2,3-dichlorobutadiene, 1-chlorobutadiene, butadiene, isoprene, 2-cyanobutadiene, acrylic acid, methacrylic acid, and methyl methacrylate.

Examples include acrylonitrile. These monomers are
It is usually used in an amount of 30% by weight or less based on the composition of the entire monoplane.

Examples of the cyclic polysulfide compound include 1,2-dithiane, 1,2. ! l-) Lithian, 1,2. '5.4-tetrathiacyclohexane, 1,2.3-)lithia-6,9
, 12-trioxytetradecane, 1,2.3-)lithia-6,9-dioxycycloundecane, 1,2.3-
) Lithia-6-ogycyclooctane, 1.2-dithia-5,all-)lioxycyclododene, 1.2
．． ! I.

4-tetrathia-7,10,15-)lyoxycyclopentadecane, 1,2,3,4.5-pentathia-8,1
1゜14-trioxycyclohexadecane, 1.2.3
．． Examples include 4°5.6-hexathia-9,1-15-trioxycycloheptadecane.

From the viewpoint of ease of obtaining a polymer having a desired viscosity by peptization and heat resistance, the cyclic polysulfide compound is preferably one represented by formula (1).

These cyclic polysulfide compounds may be added so that the amount of sulfur contained therein is Q-jXlKkk% or more based on t70prene, and is generally added in an amount of 0.1 to 10% by weight based on polyproprene.

Examples of emulsifiers include higher fatty acids and resin acids.

So-called anionic surfactants such as disproportionated rosin acids, long-chain alkyl sulfonic acids, condensation products of naphthalene sulfonic acid and formaldehyde, especially alkali metal salts, and nonionic surfactants such as polyoxyethylene nonylphenol ethers. Any one of the surfactants, etc.
More than one species is used.

As a catalyst for starting the polymerization, for example, potassium persulfate, ammonium persulfate, water peroxide, L t-butyl hydroperoxide, etc. are used. The amount used can be small compared to polymerization in the presence of elemental sulfur, which is also one of the features of the present invention.

Polymerization is carried out by mixing and stirring a monomer in which a predetermined amount of cyclic polysulfide is dissolved and an aqueous emulsion containing an emulsion.
It is carried out by adding a catalyst liquid at a temperature of 0°C and a pH of 7 to 13 in a double polymerization system.

Polymerization is carried out to a polymerization conversion rate of about 65 to 95%, and is then stopped by adding a small amount of a polymerization inhibitor.

Examples of polymerization inhibitors include thiodiphenylamine,
4-tert-butyl cateconosi, 2.2'-methylenebis-4-methyl-6=tert-butylphenol.

It is a water-soluble salt of dialkyldithimelic acid and is added in an amount of 0.01 to 2.0% by weight based on the polymer.

The polymer produced at the time the polymerization is stopped contains sulfur atoms in the main chain, has a high molecular weight, and is crosslinked, so it is insoluble in benzene. For this reason, it is virtually impossible to process the polymer directly. This can be done similarly to peptization in the production of sulfur-modified chloroprene polymers. That is, a tetraalkylthiuram disulfide and/or a thiol of the general formula R'-8H or its ionized sulfenyl form R is used as a peptizing agent.
8-MJ (Mθ is an alkali cation or ammonium, R is a linear or branched argyl group or alkylaryl group having 2 to 6 carbon atoms,
Arylcarbonyl groups, alkylcarboxyl groups, alkylnaphthyl or naphthyl groups, arylthiazole or thiazole groups or their sodium salts, arylimidazole or imidazole groups or alkylxanthate groups) can be used. Additionally, salts of formaldehyde sulfoxylates, inorganic thiosulfates,
Monosulfides, polysulfides, amine compounds.

There is nothing wrong with using a peptizing accelerator such as a morpholine compound in combination. Peptization is 01 to 5.0 for polymers.
Weight percent of peptizer or a mixture of peptizer and peptizer is added to the polymer latex at a temperature of 20-60° C. until the polymer reaches a predetermined viscosity range. Examples of the tetraalkylthiuram disulfide used for peptization include tetraethylthiuram disulfide and tetrabutylthiuram disulfide.

The desired chloroprene polymer obtained as described above can be made into polymer crumb by separation and drying in a conventional manner. For example, unreacted monomers are removed from peptized polymer latex by steam dripping under reduced pressure.
After removal and recovery, the polymer crumb can be obtained by freezing and coagulating in a conventional manner, and separating and drying the polymer.

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

Note that the cyclic polysulfide compound used in this example (
1) was synthesized according to general formula +11, (2).

R3-R-81 grudge (C~, 5ill→(0H3)3Si
HH8i (OH3)3 (υrll'1), nuclear magnetic resonance absorption spectrum, and mass spectrometry.

Example 1 A monomer solution in which 1,2,3,4-tetrathiacyclohexane having the following composition was dissolved and an emulsion were mixed and stirred under a nitrogen atmosphere, and the humidity was raised to 40°C.

Monomer liquid Parts by weight Chlorobrene 100 2.6-Ditert-butyl P-cresol O,011,2
,3,4-tetrathiacyclohexane 1.0 emulsion
Weight parts: Disproportionated potassium rosin acid 5.0 Sodium hydroxide 02 Trisodium phosphate 0.7 Distilled water 130 A polymerization catalyst liquid having the following composition was added at a constant rate using a pump and polymerized.

Parts by weight Potassium persulfate 1.0 Sodium anthraquinone β-sulfonate 0.1 Distilled water 50 Polymerization was carried out until the conversion rate reached 80%, and a polymerization inhibiting liquid having the composition shown below was added to stop the polymerization.

Part by weight Dimethylammonium dithiocarbamate o [5 Distilled water 4.0 P The proprene latex obtained up to this point was dropped into methanol, taken out and dried, and the polymer was mixed with 2
The sample was immersed in rJJ at 3°C for 40 hours and the benzene insoluble area was measured.

The results are shown in Table 1.

Next, a peptizing solution having the following composition was added and the solution was heated at 40°C for 5 minutes.
Time peptized.

Part by weight Tetraethylthiuram disulfide 1.6 Thiodiphenylamine 0.01 2,6-Ditert-butyl P-cresol o,os Chloroprene 6.0 Sodium lauryl sulfate 0.2 Distilled water 2.0 Peptized latex After removing unreacted chloroprene by a conventional steam dripping method, a chloroprene polymer was obtained by a conventional freeze-coagulation drying method.

Table 1 shows the results of measuring the amount of benzene-insoluble parts of the obtained polymer and the sulfur content after redeposition.

Next, in order to measure the physical properties of the vulcanized product of this chloroprene polymer, it was kneaded with a roll using the recipe shown in Table 2.
A vulcanized rubber sheet was prepared by press vulcanization at 0° C. for 40 minutes, and its physical properties were measured according to JIS 6301.

In addition, this vulcanizate was further heated to 100°C in a test tube.
After heat treatment at a temperature of 70 hours, the tensile properties and hardness were measured and a heat aging test was conducted.

The results are shown in Table 3.

Example 2 A chloroprene polymer was obtained in the same manner as in Example 1 except that the amount of 1.2.44-tetrathiacyclohexane in the monomer liquid was changed to 1.5 parts by weight.

Next, the benzene insoluble area, sulfur content, and physical properties of the vulcanized product of this and this product were measured in the same manner as in Example 1. The results are shown in Tables 1 and 5.

Example 3 A chloroprene copolymer was obtained in the same manner as in Example 1 except that 96 parts by weight of chloroprene and 4 parts by weight of 2,3-dichlorobutadiene were used as monomers.

Next, Example 1 was prepared for the obtained copolymer and its vulcanizate.
In the same manner as above, the benzene insoluble area, sulfur content, and physical properties were measured. The results are shown in Tables 1 and 3.

Example 4 Same treatment as in Example 1 except that 2.0 parts by weight of 1.2.5.4-tetrathia-7,10,13-)lyoxycyclobentadecane was used as the cyclic polysulfide compound. A chloroprene polymer was obtained.

Next, Example 1 for this product and a vulcanized product of this product
In the same manner as above, the benzene insoluble area, sulfur content, and physical properties were measured.

The results are shown in Table 1.3.

Example 5 The same formulation as in Example 1 was used except that 2.0 parts by weight of 1.2.3-)lithia-6,9,12-)dioxytetradecane was used as the cyclic polysulfide compound.
A chloroprene polymer was obtained.

Then, the benzene insoluble area, sulfur content, and physical properties of this product and the vulcanized product of this product were measured in the same manner as in Example 1. The results are shown in Table 1.5.

Example 6 1, 2, 3, 4.5 as a cyclic polysulfide compound
-Pentathia-8,1f, 14- ) Lioxycyclohexadecane (20 parts by weight) was used, and the same treatment as in Example 1 was carried out to obtain a chloroprene polymer.

Next, Example 1 was prepared for this product and the vulcanized product of this product.
The benzene insoluble area, sulfur content, and physical properties were measured in the same manner as above. The results are shown in Table 1.6.

Comparative Example 1 A chloroprene polymer was obtained by treating in the same manner as in Example 1, except that 0.08 parts by weight of 1.2.3.4-tetrathiacyclohexane was used in the monomer liquid. .

Then, the benzene insoluble area and sulfur content of this product were measured in the same manner as in Example 1. The results are shown in Table 1.

Table 2 Reference Example 1.2 Non-sulfur-modified type Skyplane B-3DJ (product name listed on Toyo Soda Kogyo) and sulfur-modified type Skyplane R-22J (product name listed on Toyo Soda Kogyo) are listed. The mixture recipe shown in No. 2 was kneaded with a roll and press-vulcanized at 150° C. for 40 minutes, and the physical properties of the obtained vulcanized rubber sheet were measured. The results are shown in Table 3.

As is clear from Table 3, the chloroprene polymer vulcanizate obtained by the present invention is of the conventional non-sulfur modified type;
It has better heat aging resistance than either of the sulfur-modified types, and its tensile strength is almost the same as the sulfur-modified type and is superior to the non-sulfur-modified type.

Patent applicant: Toyo Soda Kogyo Co., Ltd.

Claims (1)

[Claims] A method for producing a chloroprene polymer, which comprises subjecting chlorprene to aqueous emulsion polymerization in the presence of 01% by weight or more of a cyclic boria or ruphide compound, and then peptizing the obtained polymer.